1. Field of the Invention
The present invention relates to an image forming apparatus for reproducing an image which is read from an original or inputted from an image output apparatus on a recording medium such as a sheet of paper, and particularly to an image forming apparatus for forming an image with an additional image which represents identification information specific to or inherent in the image forming apparatus.
2. Description of the Related Art
In recent years, digital color-image forming apparatuses (copiers, printers and the like) capable of reproducing a color image with fidelity are made commercially available, and color images can be easily reproduced on recording mediums. Accordingly there is a fear that the color-image forming apparatus is unfairly used because images of bills, securities etc. whose reproduction is inhibited can be easily reproduced.
Therefore, the invention of Japanese Examined Patent Publication JP-B2 2614369 has a configuration where, when a color-image input is recorded and reproduced on a recording medium, a pattern image representing identification information inherent to an image forming apparatus is added to the color image with color material difficult to be discriminated by human eyes.
According to the configuration, the pattern image inherent to the image forming apparatus is added on bills, securities or the like which have been reproduced unfairly by the color-image forming apparatus so that the reproduced bills, the securities or the like can be prevented from being used as legal bills, securities or the like and an image forming apparatus which has performed the unfair image forming process can be identified by the added pattern image.
However, in some cases, for example, a case where a document or the like which should be prevented from being externally leaked to be kept secret has been reproduced without permission, it is necessary to identify an image forming apparatus in which the image forming process has been performed whether or not the image forming process is of color-image forming or monochrome image forming. However, a conventional image forming apparatus is configured to add a pattern image representing identification information for identifying the image forming apparatus only when a color image has been formed. The identification of image forming apparatus is carried out by the identification information added at the time of forming a color image. There is a problem that in the case of forming a monochrome image it is impossible to identify the image forming apparatus which has performed a monochrome image forming process and therefore reproduction of documents which should be prevented from leaking externally to be kept secret can not be restricted. Such a problem generally occurs in a conventional image forming apparatus irrespective of image forming type.
In Japanese Examined Patent Publication JP-B2 2614369 (corresponding U.S. Pat. Nos. 5,742,408; 5,737,100; 5,465,161; 5,257,119), by adding a specific pattern at shorter pitches than a short width of a paper sheet with a color material difficult to be identified by human eyes, the specific pattern is necessarily formed on a paper sheet on which an image has been formed, so that an apparatus which has been used for image formation can be identified. Also, in Japanese Unexamined Patent Publication JP-A 5-91316 (1993) (corresponding U.S. Pat. Nos. 5,481,377; 5,363,202), a check is performed about whether or not an add-on board which generate specific pattern is normally mounted on a reproducing machine body. When the add-on board has been mounted normally, a reproducing operation is performed, and when the add-on board has not been mounted normally, a reproducing operation is inhibited, so that a specific pattern is securely added. Furthermore, in Japanese Unexamined Patent Publication JP-A 5-14682 (1993) (corresponding U.S. Pat. Nos. 5,742,408; 5,737,100; 5,465,161; 5,257,119), when achromatic (black and white) image data has been inputted, the inputted achromatic image data is outputted without adding a pattern thereto, and when a chromatic (color) image data has been inputted, the inputted chromatic image data is added with a pattern to be outputted, so that an image quality for a reproduced monochrome image is held in an excellent state though a function for adding a specific pattern on a reproduced image has been provided.
However, in the conventional art, namely JP-B2 2614369, JP-A 5-91316, and JP-A 5-14682, since there is no configuration that only a black image and an identification information image are formed by adjusting intervals or spaces between image forming portions for respective colors and a paper sheet, for example, when a color image is formed on an identification information image formed together with a black image, it becomes impossible to identify the identification information image. Thereby, it is made impossible to identify an apparatus which has performed image forming, so that an unfaith image forming process relating to a black image of a document to be held in a secret state or the like can not be prevented from being performed.
An object of the present invention is to provide an image forming apparatus which securely forms an identification information image inherent to the image forming apparatus on an recording medium at a time of a black-image forming, by which the apparatus which has performed a black-image forming process can be identified and capable of suppressing an unfaithful black-image forming process of documents to be held in a secret state or the like.
The invention provides an image forming apparatus comprising:
a black-image forming portion for carrying out a black-image forming process for forming a black image on a recording medium;
a first color-image forming portion for carrying out a color-image forming process by which a color image is formed on a recording medium;
an identification information adding portion for adding identification information data which represents identification information inherent to the apparatus;
an identification information image forming portion for carrying out a process of forming an identification information image based on the identification information which is added by the identification information adding portion, on the recording medium at a time of the black-image forming process; and
color-image forming disabling means for disabling the color-image forming process operation of the color-image forming portion at a time of the black-image forming process of the black-image forming portion.
According to the invention, at a time of the black-image forming process the identification information image inherent to the image forming apparatus which has performed the image forming process is formed on a recording medium together with a black image. Accordingly, the image forming apparatus which has performed the image forming process is identified by the identification information image formed on the recording medium together the black image, so that an unfaithful image formation regarding a black image of a document which should be held in a secret state or the like is suppressed. Also, a color-image forming process operation in the first color-image forming portion is invalidated at a time of the black-image forming process. That is, only image forming operations in the black-image forming portion and the identification information image forming portion are made effective. Accordingly, only a black image and an identification information image are accurately formed on a recording medium at a time of the black-image forming process.
In the invention it is preferable that the image forming apparatus further comprises black-image formation inhibiting means for inhibiting performing of the black-image forming process operation in the black-image forming portion when formation of the identification information image effected by the identification information image forming portion is not allowed.
According to the invention, when identification information image inherent to an image forming apparatus which has performed image forming can not be formed on a recording medium, performing of the black-image forming process is inhibited. Accordingly, an identification information image for identifying an image forming apparatus which has performed image forming is necessarily formed on each recording medium on which a black image has been formed, and the image forming apparatus which has performed the image forming process is securely identified from an image on which a black image has been formed. Accordingly, performing of an unjust image forming process regarding a black image of a document to be held in a secret state or the like can securely be suppressed.
In the invention it is preferable that a recording medium on which an image is formed is conveyed in a state where the recording medium is opposed to the respective image forming portions at predetermined intervals in between and the color-image forming disabling means opens up the predetermined intervals between the recording medium and the color-image forming portion at a time of the black-image forming process in the black-image forming portion.
According to the invention, the color-image forming operation in the first color-image forming portion is invalidated at a time of the black-image forming process by conveying the recording medium in a state where the interval between the color-image forming portion and the recording medium is opened up largely. Accordingly, a color image and an identification information image is further securely prevented from being formed on the recording medium.
In the invention it is preferable that the image forming apparatus comprises further one or more color-image forming portions, the first color-image forming portion and the one or more color-image forming portions are disposed adjacent to one another along a recording medium conveying direction, and the color-image forming disabling means opens up the intervals between the respective color-image forming portions and the recording medium largely in an integrated manner.
According to the invention, the color-image forming operations in the color-image forming portions are invalidated at a time of the black-image forming process by conveying the recording medium in a state where the intervals between the plurality of the color-image forming portions and the recording medium are opened up largely in an integrated manner. Accordingly, by a very simple configuration and control, a color image and an identification information image can securely be prevented from being formed on a recording medium at a time of the black-image forming process.
In the invention it is preferable that each of the image forming portions accommodates image forming material for each color, and an amount of the image forming material accommodated in the identification information image forming portion is made larger than an amount of the image forming material accommodated in each of the color-image forming portions.
According to the invention, a larger amount of image forming material than that in each color-image forming portion is accommodated in the identification information image forming portion. Accordingly, even when black-image forming process frequency is high, only the image forming material in the identification information image forming portion is prevented from being consumed earlier, so that an identification information image can be formed over a long time on a recording medium on which a black image has been formed.
The invention further provides an image forming apparatus comprising:
a plurality of image forming portions for forming an image on a recording medium, disposed adjacent to one another along a direction of conveying the recording medium,
the recording medium being conveyed so as to oppose each of the plurality of image forming portions at predetermined intervals in between in forming an image thereon,
the plurality of image forming portions including:
a black-image forming portion for carrying out a black-image forming process for forming a black image on the recording medium; and
a plurality of color-image forming portions for carrying out a color-image forming process for forming color images on the recording medium, respectively; and
an identification information adding portion for adding identification information data which represents identification information inherent to the apparatus,
wherein a single color-image forming portion of the plurality of color-image forming portions which is positioned adjacent to the black-image forming portion performs an identification information image forming process for forming an identification information image, based on the identification information data which has been added by the identification information adding portion, on the recording medium at a time of the black-image forming process,
the image forming apparatus further comprising:
color-image forming disabling means for disabling color-image forming process operations of color-image forming portions of the plurality of color-image forming portions except the single color-image forming portion, at a time of the black-image forming process of the black-image forming portion.
According to the invention, the single color-image forming portion of the plurality of color-image forming portions which is positioned adjacent to the black-image forming portion corresponds to the identification information image forming portion. An identification information image inherent to the image forming apparatus is formed together with a black image on a recording medium at a time of the black-image forming process, the color-image forming process operations of the color-image forming portions except the single color-image forming portion for performing the identification information image forming process are invalidated at a time of the black-image forming process, and only the image forming operations of the black-image forming portion and the single color-image forming portion as the identification information image forming portion positioned adjacent to the black-image forming portion are made effective. In this way at a time of the black-image forming process, only an black image and the identification information image are accurately formed on the recording medium. Accordingly, the image forming apparatus which has performed the black-image forming process is identified by the identification information image on the recording medium, and an unfaithful black-image forming process regarding documents to be held in a secret state or the like is suppressed.
In the invention it is preferable that the image forming apparatus further comprises black-image forming inhibiting means for inhibiting carrying-out of black-image forming process operation of the black-image forming portion, when the formation of the identification information image by the single color-image forming portion is disabled.
According to the invention, when the identification information image inherent to the image forming apparatus can not be formed on the recording medium, performing the black-image forming process is inhibited. Accordingly, a black image formed on a recording medium necessarily includes the identification information image for identifying the image forming apparatus, and the image forming apparatus which has performed the image forming process is securely identified by the identification information image on the recording medium. Thus, unfaithful black-image formation of documents to be held in a secret state or the like can securely be suppressed.
In the invention it is preferable that the color-image forming disabling means opens up the predetermined intervals between the respective color-image forming portions except the single color-image forming portion and the recording medium at a time of the black-image forming process of the black-image forming portion.
According to the invention, color-image forming process operations of the color-image forming portions except the single color-image forming portion at a time of the black-image forming process are invalidated by conveying the recording medium in a state where the intervals between the color-image forming portions and the recording medium are largely opened up. Thereby, the color-image formation on the recording medium can be more securely prevented at a time of the black-image forming process and only a black image and an identification information image are formed thereon.
In the invention it is preferable that each of the image forming portions accommodates image forming material for each color, and an amount of the image forming material accommodated in the single color-image forming portion is made larger than an amount of the image forming material accommodated in each of the plurality of color-image forming portions except the single color-image forming portion.
According to the invention, a larger amount of image forming material than that accommodated in the other color-image forming portions is accommodated in the identification information image forming portion which is the single color-image forming portion of the plurality of color-image forming portions which performs an identification information image forming process. Accordingly, even when a frequency of the black-image forming process is high and the identification information image forming portion is a color-image forming portion for forming an image of one color at a time of the color-image forming process, only the image forming material in the identification information image forming portion is prevented from being consumed earlier, so that an identification information image can be formed over a long time on a recording medium at a time of the black-image forming process.